A conventional subscriber television system provides programming in a digital format such as MPEG-2, which is an established standard for the compression of audio and video information. The distribution mechanisms employed by a conventional subscriber televisions system include satellite, terrestrial and cable communications networks. A relative newcomer for the distribution of digital program material is the broadband packet-switching network.
The broadband packet-switching network and the television network worlds have traditionally been distinct and separated by a wide gap technologically. The distribution and broadcast of television content has been traditionally a one-way technology, with a high reliability of service. By contrast, packet-switching networks are full duplex and were not originally designed to offer high reliability or Quality of Service (QoS).
An example of a packet-switching network is an Internet Protocol (IP) network, which is a “connectionless” network. In connectionless network, no connections or paths are established prior to a source being able to communicate with a destination. Instead, a packet switcher or router forwards each packet based on a path or route that is dynamically determined at the time the packet switch or router receives the packet. Consequently in packet-switching networks, each packet transmitted from the source to the destination may follow a different path through the network. Due to different delays from following different paths, the packets in a packet-switching network may arrive at the destination in a completely different order than they were transmitted by the source.
A need exists to bridge the gap between the television distribution technology and packet-switch network technology. Digital program streams are synchronous streams that are normally played out from a digital encoder or multiplexer in an industry standard format known as Digital Video Broadcast/Asynchronous Serial Interface (DVB/ASI). Thus, what is sought is an apparatus and method for carrying a transport stream over a packet-switch network and re-transmitting the transport stream. What is also sought is an apparatus and method for receiving a variably delayed stream of network frames transmitted through a packet-switch network and playing out a synchronous stream of transport packets, wherein the transport packets were carried in the network frame stream. Furthermore, what is sought is an apparatus and method for receiving a transport stream and selectively including content of the transport stream in network frames for transmission over a packet-switching network.